1. Field
This disclosure relates to a method for chemical modification of a graphene edge, graphene with a chemically modified edge and devices including the graphene.
2. Description of the Related Art
Graphite is an allotropic form of the element carbon having a stacked structure of two-dimensional planar sheets in which carbon atoms are bonded in an extended fused array of hexagonal rings. The layers are stacked parallel to each other in a three-dimensional crystalline long-range order. There are two allotropic forms with different stacking arrangements, hexagonal and rhombohedral. A single layer of the extended fused array is often referred to as graphene.
A plurality of graphene layers is often referred to in the art as graphite. However, for convenience, “graphene” or “a graphene sheet,” as used herein, may comprise one or more layers of graphene. A graphene sheet may have advantageous properties different from those of other materials. In particular, electrons may move on the graphene sheet as if they have zero mass. Thus, electrons on the graphene sheet may move at the velocity of light in a vacuum. Electron mobility on a graphene sheet has been observed to be from about 20,000 square centimeters per volt seconds (cm2/Vs) to about 50,000 cm2/Vs. Further, a graphene sheet may exhibit unusual half-integer quantum hall effects for electrons and holes.
Since the electrical properties of a graphene sheet, with a given thickness, may change depending on its crystallographic orientation, the electrical properties of the graphene sheet may be controlled by selecting the crystallographic orientation of the graphene sheet. Thus, devices using a graphene sheet can be designed to have different electrical properties. Further, for some devices or applications, graphene having different physical or chemical properties is desirable. It is therefore desirable to have a process that provides a chemically modified graphene having different physical or chemical properties.
The electrical properties of a graphene sheet may be compared with those of a carbon nanotube (“CNT”), which is known to exhibit metallic or semiconducting properties depending on the chirality and diameter of the CNT. A complicated separation process may be needed in order to take advantage of such metallic or semiconducting properties of CNTs. A graphene sheet may thus have economic advantages over CNTs because the purification process used with synthesized CNTs may be avoided. Thus, graphene sheets may be less expensive than CNTs. Therefore, it may be desirable to use a graphene sheet in carbon-based electrical or electronic devices in place of CNTs.